Turboshaft Blade Root Test Rig for Combined Fretting Fatigue

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Solution Overview

Problem

Current test rigs fail to reliably reproduce the complex tribological stresses and low-cycle fatigue experienced by turbine engine blade-disc attachments, particularly in terms of high-frequency vibrations and high-temperature conditions, limiting the analysis of fretting fatigue damage.

Innovation Solution

A test rig that combines high-frequency tribological stress and low-cycle fatigue, featuring a turbine engine rotor blade root-shaped test piece inserted into a complementary groove, with heating and vibratory loading capabilities, and adjustable positioning to simulate actual operating conditions, including high temperatures and complex resonance modes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Speed

If conventional test means are used to study fretting fatigue damage, then maximum frequencies of 100 Hz can be reached, but low-cycle and high-cycle cycles cannot be combined at high temperature

Engineering Contradiction:

Improvetest frequencyVSAvoidability to combine stress cycles and temperature conditions

Core Design Contradiction:

SpeedVSAdaptability or versatility

Solution Approach 1:

The patent merges multiple testing capabilities into a single test rig that can simultaneously apply low-cycle fatigue loading, high-frequency vibratory loading, and high-temperature heating. This integration allows the reproduction of complex operating conditions where centrifugal forces, vibrations, and thermal effects occur together, resolving the contradiction between achieving high test frequencies and maintaining versatility in stress combination and temperature control

Inventive Principle:

Principle #5Merging (Combining)

2Reliability

If test means aim to reproduce contact geometry similar to blade-disc attachment, then representativeness is improved, but ability to combine stresses is limited

Engineering Contradiction:

Improverepresentativeness of blade-disc attachmentVSAvoidability to combine stresses

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent employs dynamic loading capabilities that allow independent control of low-cycle fatigue loads and high-frequency vibratory loads while maintaining the representative blade-disc contact geometry. The test rig can dynamically adjust loading parameters and combine different stress types, resolving the contradiction between geometric representativeness and stress combination versatility

Inventive Principle:

Principle #15Dynamics

3Ease of manufacture

If simple alternating sliding cycle is used to load contact surfaces, then test simplicity is improved, but tribological stress accuracy deteriorates

Engineering Contradiction:

Improvetest simplicityVSAvoidtribological stress accuracy

Core Design Contradiction:

Ease of manufactureVSMeasurement precision

Solution Approach 1:

The patent changes the loading parameters from simple alternating sliding cycles to complex combined loading cycles that include low-cycle fatigue components, high-frequency vibratory components, and thermal parameters. This allows accurate reproduction of tribological stresses while maintaining test feasibility through systematic parameter control

Inventive Principle:

Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

Enables accurate reproduction of the stresses and conditions experienced by rotor blades during operation, allowing for detailed characterization of fretting fatigue and the evaluation of material pairs under realistic conditions, including high temperatures and complex stress combinations.

Implementation Method 1

The rig also comprises a heater for heating the test pieces

Methodology Applied

Scientific EffectHeating: Heating

Implementation Method 2

means for loading the test pieces in a vibratory manner so as to carry out a fretting fatigue test

Methodology Applied

Scientific EffectVibration: Vibration

Implementation Method 3

a second test piece which is connected to traction means for loading the second test piece so that it bears against the or each bearing surface of the first test piece and carrying out a low-cycle fatigue test

Methodology Applied

Scientific EffectTensile stress: Tension

Data Source

PatentUS9869621B2Test bench combining high-frequency tribological stress and oligocyclic fatigue, on a blade disk of turboshaft engine of an aircraft including a test piece having a portion with a shape of a blade root of a rotor and is engaged in a groove shape complementary to another test piece

Publication Date: 2018.01.16 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A test rig combining high-frequency tribological stress and low-cycle fatigue. The test rig includes a first test piece which is fixed to a frame and defines at least one bearing surface, a second test piece which is connected to an actuator for loading the second test piece so that it bears against the at least one bearing surface of the first test piece, a heater configured for heating the test pieces and a vibration generator, such as a shaker, for loading the test pieces in a vibratory manner so as to carry out a fretting fatigue and low-cycle and high-cycle fatigue test. One of the test pieces includes a portion in the shape of a turbine engine rotor blade root and which is inserted in a groove having a shape that is substantially complementary to the other test piece so as to reproduce a turbine engine blade-disc attachment.